1. Field of the Invention
This invention relates to a drill jig for locating holes to be drilled in a workpiece, and more particularly to a drill jig for locating in-line holes to be drilled in a workpiece.
2. Description of the Related Art
In the past, drilling has been widely used for processing workpieces. In some cases, rows of aligned holes are formed in a workpiece. For example, aligned holes are often formed in modular units of a DIY (do it yourself) furniture in order to combine the modular units by means of pins or tenons to form finished furniture. Referring to FIG. 1, DIY furnitures usually include two upright mounting plates 1. Each of the mounting plates 1 has two rows of aligned holes 2 in the inside face thereof. Each hole of one of the two rows of holes 2 is aligned with the corresponding one of the other row of holes 2, so that every four holes 2 are arranged at the same level when two mounting plates 1 are set up with two inside faces facing one another. Four tenons 3 may be inserted into four holes 2 at the same level in order to support a partition plate 4. Four additional tenons 3' can be inserted into four holes 2 at a lower level in order to support the partition plate 4 at a lower level. In this way, the level of the partition plate 4 with respect to the mounting plates 1 can be adjusted by inserting the tenons 3 or 3' into the holes 2 at different levels. To ensure the accuracy of the location of the holes 2 in the mounting plates 1, drill jigs are often used to facilitate the formation of the holes 2.
Referring to FIG. 2, a conventional drill jig is used to locate the holes 2 to be drilled in the mounting plate 1. The drill jig includes a pair of parallel shafts 10 and four limiting pieces 11 which are provided on the ends of the parallel shafts 10. The limiting pieces 11 clamp on two opposite edges of the mounting plate 1 in order to hold the parallel shafts 10 in position. A pair of elongated guide bars 12 are mounted slidably and transversely on the parallel shafts 10. The guide bars 12 are formed with a series of aligned and equally spaced through-bores 13. The drill jig further includes locking bolts 14 which lock the guide bars 12 on the parallel shafts 10.
A guide block 15 is mounted detachably and slidably to one of the guide bars 12. The top face of the guide block 15 has a bore in which a bushing 16 is received. When using the conventional drill jig, the guide bars 12 are initially adjusted to the desired positions on the mounting plate 1 and locked by means of the locking bolts 14. The guide block 15 is moved along the one of the guide bars 12 so as to align the bushing 16 with one of the through-bores 14. A drill bit (not shown) is then extended into the bushing 16 and is rotated in order to bore a hole 2.
After one hole 2 has been bored, the guide block 15 is moved so as to align with another one of the through-bores 13. The above procedure is then repeated to form another hole 2 in the mounting plate 1.
The drawbacks of the conventional drill jig are as follows:
1. The drill jig has so many components that the manufacturing costs for these components are high. Therefore, the drill jig is expensive.
2. The time for mounting the drill jig onto a workpiece is long and the operation procedures of the drill jig is complicated. If the sizes of the workpieces are different, frequent mounting and dismounting is unavoidable. This inconveniences the users and increase the overall working time.